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The Collaborative International Dictionary of English v.0.48 (gcide)

Conoid \Co"noid\ (k[=o]"noid), n. [Gr. kwnoeidh`s conical;
kw^nos cone e'i^dos form: cf. F. cono["i]de.]
1. Anything that has a form resembling that of a cone.
[1913 Webster]

2. (Geom.)
(a) A solid formed by the revolution of a conic section
about its axis; as, a parabolic conoid, elliptic
conoid, etc.; -- more commonly called {paraboloid},
{ellipsoid}, etc.
(b) A surface which may be generated by a straight line
moving in such a manner as always to meet a given
straight line and a given curve, and continue parallel
to a given plane. --Math. Dict.
[1913 Webster]


Ellipsoid \El*lip"soid\, n. [Ellipse -oid: cf. F. ellipsoide.]
(Geom.)
A solid, all plane sections of which are ellipses or circles.
See {Conoid}, n., 2
(a) .
[1913 Webster]

Note: The ellipsoid has three principal plane sections, a, b,
and c, each at right angles to the other two, and each
dividing the solid into two equal and symmetrical
parts. The lines of meeting of these principal sections
are the axes, or principal diameters of the ellipsoid.
The point where the three planes meet is the center.
[1913 Webster]

{Ellipsoid of revolution}, a spheroid; a solid figure
generated by the revolution of an ellipse about one of its
axes. It is called a prolate spheroid, or prolatum, when
the ellipse is revolved about the major axis, and an
oblate spheroid, or oblatum, when it is revolved about the
minor axis. Ellipsoid


Ellipsoid \El*lip"soid\, Ellipsoidal \El`lip*soi"dal\, a.
Pertaining to, or shaped like, an ellipsoid; as, ellipsoid or
ellipsoidal form. Elliptic